In recent years, since large-capacity recording media have become available and broadband networks have been developed, systems for distributing a digital content have been getting popular. In such a system, a digital content that is a digitized work such as a movie or music (hereafter simply referred to as “a content”) is distributed in a form of a recording medium on which the content is recorded, or distributed via a broadband network. In such a system, a copyright for the content should be protected, and copying and playing back of the content should be permitted only under restrictions based on an agreement with a copyright holder. As a conventional technique for protecting a copyrighted work against unauthorized copying that is not permitted by a copyright holder, a method using digital watermarks is well known. A common system using digital watermarks includes a content provider's terminal apparatus (a digital watermark embedding apparatus) and a content user's terminal apparatus (a digital watermark detection apparatus). The provider's terminal apparatus (the digital watermark embedding apparatus) provides a mechanism for embedding copyright information or the like in the content. For example, the provider's terminal apparatus records the copyright information on a recording medium such as a disc. The user's terminal apparatus (the digital watermark detection apparatus) provides a mechanism for controlling playing back of the content based on the copyright information detected from the content recorded on the recording medium. If a content in which copyright information has been embedded is copied without authorization, this means that the copyright information is also copied. Therefore, with the mechanisms above, it becomes possible to control (e.g. to stop) playing back of a content copied without authorization, by detecting the copyright information.
The digital watermark technique is described in detail in Patent Documents 2 and 3. Also, Patent Document 1 discloses a technique for preventing unauthorized copying by embedding copy control information in a content using the digital watermark technique.
Meanwhile, digital video cameras (hereinafter referred to as “camcorders”) have been getting popular as apparatuses for recording video data shot for personal purposes, for making a record of a child's growth for example. A camcorder is capable of digitally recording video data on a recording medium (e.g. an optical disc such as a DVD, a SD memory card and so on), and the user can easily play back and enjoy the video recorded on the recording medium using a playback apparatus (e.g. a DVD recorder). Also, now it is common to copy a personally recorded video to other recording media and distributing them to relevant parties.    Patent Document 1: U.S. Pat. No. 5,943,422    Patent Document 2: Japanese Laid-open Patent Application Publication No. H9-191394    Patent Document 3: Japanese Laid-open Patent Application Publication No. H9-191395